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Hereditary inclusion body myopathies (HIBM) are a heterogeneous group of genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individual patients, but all share similar structural features in the muscles. HIBMs are a group of muscle wasting disorders, which are uncommon in the general world population. One autosomal recessive form of HIBM is known as IBM2, which is a common genetic disorder amongst people of Iranian Jewish descent. IBM2 has also been identified in other minorities throughout the world, including people of Asian (Japanese and others), European, and South American origin, as well as Muslim patients in the Middle Eastern, Palestinian, and Iranian origin. In Japan and many East Asian countries, this disorder is known as Distal Myopathy with Rimmed Vacuoles (DMRV). IBM2 causes progressive muscle weakness and wasting. Muscle wasting usually starts around the age of 20 – 30 years, although young onset at 17 and old onset at 52 has been recorded. As such, it affects the most productive times of our lives. It can progress to marked disability within 10 – 15 years, confining many patients to the wheelchair. The weakness and severity can vary from person to person. In some, weakness in the legs is noticed first. In few others, the hands are weakened more rapidly than the legs. Weakness is progressive, which means the muscle become weaker over time. IBM2 does not seem to affect the brain, internal organs or sensation. The quadriceps are relatively spared, and remain strong until the late stages of disease, which is the reason IBM2 is often referred to as Quadriceps Sparing Myopathy (QSM). ==Classification== Types of hereditary inclusion body myopathy: # An autosomal dominant form (IBM1) where the quadriceps are one of the first muscles to become weak. Needham (2007) lists IBM1 under OMIM 601419: () # An autosomal recessive form (IBM2), common among people of Middle Eastern and Jewish heritage. This form mainly affects leg muscles, but with an unusual distribution that spares the quadriceps: a so-called quadriceps-sparing myopathy (QSM), the quadriceps are among the last muscles to become weak. See: OMIM # 600737.() Also see OMIM:605820(DMRV)(). # Nonaka distal myopathy with rimmed vacuoles, essentially a form of IBM2. See: OMIM # 605820: () # Inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD), is linked to a slightly different gene, encoding valosin-containing protein (VCP) on chromosome 9 (located at 9p13-p12). See: OMIM # 167320 () # Inclusion body myopathy-3 (IBM3) is linked to mutations in a gene encoding myosin heavy chain II proteins on chromosome 17 (located at 17p13.1). See: OMIM # 605637 () More types of HIMBs, linked to other genes, may be identified in the future. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hereditary inclusion body myopathy」の詳細全文を読む スポンサード リンク
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